This invention relates to a cutting apparatus suitable for cutting a moving web into segments.
Many paper and fabric products are manufactured on production lines that include continuous webs of material travelling at high speeds while they are coated, treated, or otherwise operated upon. Such webs are typically cut at some point in the process into segments of a desired size. Although it is highly desirable, from a production point of view, to run the webs at the highest possible speeds, such high speeds complicate the cutting process. In fact, at very high speeds virtually all available cutting apparatuses are unworkable.
A common prior cutting arrangement has simply been to reciprocally drive a cutting blade positioned above the web in a down-and-up stroke. In order to cut a momentarily stationary segment of the web, various web clamping arrangements have been proposed to instantaneously clamp the web upstream of the cutting blade during the actual cutting operation. At very high web speeds, however, a quantity of web can "pile up" behind the clamping arrangement and this slack must be taken up before the next cutting cycle can begin. Furthermore, the speed of operation of such a cutting apparatus is itself limited. As can be appreciated, even with large driving systems, the typically heavy cutting blade has a limited speed of movement in its down-and-up cutting cycle. One example of a blade-type cutting apparatus is shown in Soderberg U.S. Pat. No. 2,130,818.
As is explained in detail below, the present invention contemplates the use of crossed wire segments, employing a moving point of contact, as a cutting system. Although wire-type cutters have been known in the past, typically they have been employed in cutting situations not facing the problems of high speed moving webs that are to be transversely cut. For example, single wire cutters are shown in Keck U.S. Pat. No. 3,838,621 and in Schumacher U.S. Pat. No. 1,197,553. In the Schumacher arrangement a single wire interacts with an elongated frame to define the cutting point and in the Keck patent non-interacting cutting wires longitudinally cut blocks of clay into brick-shaped elements.
Three U.S. Pat. Nos. to Criner (2,110,290; 2,182,281; and 2,906,309) all disclose band saw-type cutting devices in which the saw blade is twisted to form a figure eight. A series of these figure eight saw blades is employed for bread slicing operations.
As will be evident to those skilled in the art, none of these prior suggestions is particularly suitable for solving the problem of efficiently and neatly providing a continuous series of transverse cuts across the width of a web moving at high speeds.